The present invention relates to a device for cutting strip material in a wrapping machine. One conventional device of the type in question, widely utilized for cutting a continuous strip of silver paper (i.e., aluminum foil-paper laminate) into discrete lengths or wrappers suitable for enveloping groups of cigarettes, importantly includes a transverse blade and a longitudinal blade.
The blades rotate about mutually parallel axes disposed at right angles to the feed direction of the strip material, and operate in conjunction with corresponding reaction means rotatable about axes parallel to the axes of rotation of the blades. The strip is fed in a continuous fashion, descending freely and thus substantially unchecked during its downward movement, to the point of engaging at bottom against a stop which serves both as a travel limiter and as a means for ensuring that the cut wrapper is positioned correctly in relation to the commodity (i.e. article) that is to be wrapped.
The blades and their respective reaction means are positioned on opposite sides of the descending strip, and timed to cut into the material at a given moment during its descent.
Such cutting devices are affected by drawbacks when operated at the high speeds typical of more modern wrapping machines.
While a faster operating speed of the blades alone is easily obtainable, an increase in the feed rate of the strip material is not so readily achieved. In effect, wrapping materials of this type are, in general, extremely lightweight, so that operation of the relative feed means at a higher speed does not necessarily translate into a correspondingly faster passage of the strip through the cutting device. Moreover, a faster rate of feed results in a more violent impact of the transverse leading edge of the strip against the stop, and consequently in damage to that leading edge.